A smart entry system is one of vehicle communication systems for realizing various functions in a vehicle based on a wireless communication between a mobile device carried by a user and a vehicle mounted device equipped to a vehicle. The smart entry system performs an authentication through the wireless communication between the mobile device and the vehicle mounted device, and can perform operation desired by a user, such as unlocking of a door locking device, opening of a trunk door, or an engine start on the basis of an authentication result, even without using a mechanical key.
In recent years, a communication system has been proposed (refer to Patent Literature 1) as follows. The communication system can execute a predetermined application program on a mobile terminal, such as a smartphone, display a command or vehicle information which is acquired through the mobile device, or can transmit a command or information to the vehicle from the mobile terminal directly or through the mobile device.
In addition, a technique in which the smartphone per se automatically recognizes getting-off of the user from the vehicle, and acquires and stores a parking position as GPS data is disclosed (refer to Non Patent Literature 1).
In a conventional smart entry system according to Patent Literature 1, a radio wave of an LF (long wave) band (hereinafter abbreviated as “LF radio wave”) is periodically transmitted from the vehicle, and the mobile device receives the LF radio wave, and responds to the vehicle with a radio wave of an RF (high frequency) band (hereinafter abbreviated as “RF radio wave”), to thereby estimate a mobile device position in the vicinity of the vehicle. Because the LF radio wave can control a propagation distance, an output is set so that the LF radio wave reaches only the vicinity of the vehicle, taking security or a dark current into consideration.
As described above, in the vehicle communication system, a position estimation of the mobile device is an important factor in functioning the system. If an estimatable range of the distance from the vehicle to the mobile device is long, a variety of convenience can be provided to the user. However, in the currently used system, the vehicle side has an initiative of the communication, and with consideration of generation of dark current which is an electric problem and an unlock of the vehicle door by the mobile device in response to a receiving of LF radio wave from the vehicle which is a problem on the ensuring of security, it is difficult to increase a wireless communication range.
In addition, there is no disclosure or suggestion of a technique for operating in conjunction with the vehicle or the mobile device with the use of the parking position stored in the smartphone.